A corresponding arrangement is described, for example, in EP 1 339 596 B1. In the arrangement shown in that document, the spiral-toothed gear, which is designed specifically as a worm gear here, is embodied by a built-up gear. Built-up gears, which frequently consist of metallic components to achieve the required strength, but frequently have a gear rim consisting of plastic especially to achieve quiet running at the same time, are known, in principle. Such a built-up gear is described, in addition, for example, in WO 2001/44694 A1.
However, the spiral-toothed gear known from EP 1 339 596 B1 as well as a built-up gear disclosed in WO 2005/038303 A1, which was published later, have the advantage over the built-up gear described in WO 2001/44694 A1 that they are self-centering. In these, the two outer disks, which together form the spiral-toothed gear with the gear rim, have axially directed projections, which pass through the gear rim and mesh with corresponding depressions of the respective other, opposite outer disk. As a result, self-centering is achieved, which leads to improved transmission of power and also simplifies the assembly of the spiral-toothed gear. However, it is common to all the above-mentioned solutions that the mounted spiral-toothed gear or gear must be pushed over a corresponding pinion for use in the steering gear of a rack and pinion steering. In view to the connection between the spiral-toothed gear and the pinion, which must be such as to rotate in unison, this makes it necessary to observe narrow shape and position tolerances of the parts, so that tolerances that may possibly nevertheless occur lead to refinishing or even to rejects, as a result of which the manufacturing costs increase in a disadvantageous manner. In addition, the effort needed for assembly to embody a steering gear comprising a built-up spiral-toothed gear and a pinion is still comparatively great.
In the solution described in EP 1 339 596 B1, ring-shaped spacers consisting of an elastic material, which have a certain buffering action in the axial, radial and even tangential directions according to the statements made in that document, are arranged between the two outer disks or flanges of the spiral-toothed gear and the gear rim thereof. However, it shall be pointed out that the damping effect of the spacers, which are designed as flat rings with a plurality of radially rising projections arranged distributed over the circumference, is still rather weak. However, due to their shape and the small thickness of material, the spacers disclosed in the document do not make it basically possible to affect the characteristics in a specific manner in the individual directions.